Fans were complaining about how Fluttershy's tambourine doesn't fit in too well with a rock band. But when you think about it, it's the perfect instrument for her.
In fact, everyone in the Humane Five plays an instrument perfectly suited for their character.
Rainbow Dash: The electric guitar is for those guys who love to rock out and "be awesome".
Applejack: The bass guitar has a bit of a country flair, if played in the right hands.
Rarity: The key-tar is basically a piano. A classical, elegant instrument for an elegant girl like her.
Pinkie Pie: The drums are loud, attention-grabbing, and just fun to play on. And Pinkie Pie LOVES to be loud.
Fluttershy: The tambourine is perfect for this girl. It's quiet. It doesn't gain much attention. It's mostly a background thing, which is good for Fluttershy, as she's not one for attention.
Offering human Twilight a Theremin to play is a good idea on Pinkie's part, it is one of the few musical instruments that does not require hands to use so a pony or a human could play it the same way. Twilight has no idea how to play one mind you but it shows Pinkie's out of the box thinking at work.
Why would Sunset have a book that would be a direct line of communication to pony Celestia? Consider that Celestia trained Spike to act as the same function for Twilight once he was hatched and Celestia took her in as her student as to allow them to keep in touch as they traveled the world. As a former student of Celestia, Sunset wouldn't have had a dragon, so this was the solution Celestia had come up.
Moreso, as Word of God has considered the dragon egg test as unpassable, Celestia providing this book system to all her former personal students as to allow them to keep in touch over distances makes sense.
Princess Twilight tells her pony friends not to come with her through the portal because having two of everyone around would be weird. This is foreshadowing The Stinger where we finally see the Equestria Girls' world's version of Twilight (and Spike, who does appear to be a normal dog).
The end of the film reveals that Sunset Shimmer knows how to play the guitar. How could she have such a skill? She dated Flash Sentry, and it's not impossible that a boyfriend might try to teach his girlfriend how to play an instrument that he can play himself.
Alternatively, both having mad guitar skills could have been something that helped bring them together.
It could be likely she'd picked it up to learn the necessary dexterity for being human. She'd initially have the same problems Twilight did, and considering her motivations, realized she'd quickly need to get a hang of hands. So, coupled with her drive for success, her being good at guitar is a great way for her to learn to blend in.
Rainbows are commonly believed to have seven colors. In the climax, Sunset Shimmer adds her own power to the friendship rainbow as the seventh member of the Humane Six.
Case in point: Red - Sunset Shimmer (hair color), Orange - Applejack (skin color), Yellow - Fluttershy (skin color), Green - Pinkie Pie (odd one and color out), Blue - Rainbow Dash (skin color, though it is actually cyan, but still close enough), Indigo - Twilight Sparkle (hair color, which is closer to this than Rarity's hair), and Violet - Rarity (hair color, which is closer to this than Twilight's hair)
There's also this: When you consider the Elements of Harmony, Rainbow is red, Applejack is orange, Fluttershy's pink replaces yellow (presumably because the yellow would be harder to see against the gold borders of the Elements or too easily confused with the orange), Twilight's magenta element replaces green ( as greenis oftenconsidered amagicalcolornote Ironically, none of these tropes apply to Twilight herself.), then it's Pinkie Pie's blue Element, and in terms of the Mane Six, you then have Rarity with purple. This leaves indigo for Sunset Shimmer, which is the one color that is always the one left off of six-colored rainbow drawings and some people even claim it doesn't even count as a color. Sunset Shimmer is constantly being left out of the group activities and is the person everyone tends to ignore and shun, and even in a meta sense, she's not counted as an official member of the Mane Six.
Alternatively, If you include Spike and Vinyl in the rainbow, then you get the 7 colors of the rainbow plus pink and white. Sunset is red, Applejack is orange, Fluttershy is yellow, Spike is green (as is his artwork in the credits), Rainbow is blue, Vinyl is indigo (she doesn't say a word, unlike all the others, and so gets the color that most people who make a 6 color wheel would ignore), Twilight is violet/purple, Pinkie gets pink, and Rarity gets white.
The Rainbooms are each unhappy with how the band is going because, much like the first film, their Elements of Harmony are being betrayed.
Rarity: Designs costumes for the group, but is told they don't matter (her generosity is being spit on).
Rainbow Dash: Claims that she acts in the best interests of the group and thinks the others don't try (she thinks they're not being loyal to her).
Fluttershy: Writes songs, but is ignored (the others are acting unkind).
Pinkie Pie: Is bored and angry with the group's tensions because they aren't having fun.
Applejack: Is being honest with what's going on and is trying to diffuse tensions when Rarity and Rainbow get irritated, but it crosses into Brutal Honesty and just makes people more angry back at her.
Twilight surmises The Power of Friendship doesn't activate when they first try it because they need to trigger it through music now. Maybe. Or maybe the group's underlying tensions that erupt during the climax are already too disruptive to their unity.
Even more fridge brilliance, with the shift in music between the shorts and the film. Pinkie Pie is uncontrollably wild, Fluttershy is hypnotizing, and Applejackcan melt faces with a bass. You expect the Rainbooms to, well, RainbowRock. Instead, we get a bored repetition and half-attentive playing, which is more typical of girl-group pop-oriented music from the film than the energetic and enjoyable rock the shorts promised. Something must have happened between the "let's rock" and show-stealing phases, and that something is that the band started falling apart.
Why is Rainbow Dash Flanderized into an egotistical braggart? Pony Rainbow has undergone Character Development thanks to incidents like Mare-Do-Well and the Wonderbolt academy that have humbled her and made her a better person. Human Rainbow, as far as we know, hasn't, and to the contrary is the leader of a band that has acquired magical powers since the first film. No wonder she's cockier than we expect.
Likewise, why is human Fluttershy singing on stage in front of everyone when pony Fluttershy has stage fright? Because they're slightly different in that human Fluttershy had no fear until Snips and Snails directly shined the spotlight on her, while pony Fluttershy is still taking baby steps towards doing so. It probably helps that she was providing backing vocals as well as playing a tambourine, an instrument that isn't particularly loud or prominent.
In regards to both of the above, also remember how the Humane Five were estranged from each other for quite some time. It's friendship that's led to their pony incarnations to go through Character Development; without the group together to teach each other lessons and balance each other out, all of their vices are probably a bit closer to the surface.
At one point during the argument in the trap room under the stage, Rainbow Dash brags "I'm the one who writes all the songs," prompting Fluttershy to complain that she writes songs as well, it's just that Rainbow never lets them play any of them. While it's certainly true that Dash needs to learn about allowing others to influence the band, it's easy to miss the incredible truth there: Rainbow Dash has written every song we've heard them play. That not only includes the obvious "Awesome as I Wanna Be" , but also "Better Than Ever" and "Shake Your Tail!" Forget how good Rainbow is at sports, it seems that in the human world songwriting is her true talent.
While it's true that Fluttershy's song is used directly as a counter to the Sirens' spell, it should be noted that she wrote it well before the crisis even occurred. In other words, the lyrics to the song she wrote were a message she has been wanting to sing out for a long time during her normal, everyday life: Gonna break out / Set myself free, yeah / Let it all go / Just let it be, yeah etc.
"Under Our Spell" isn't just the Dazzlings bragging that the student body is under their influence, but also deals with how the Rainbooms are falling apart.
It seems a little odd Twilight is having trouble writing a musical counter-spell after how prominent music has been in the show since day one, not to mention her off-key singing when they try the song the first time when previously she's had no trouble singing. However, all previous songs are off-the-cuff spontaneous instead of pre-written, and she's unfamiliar with how the group plays their instruments since they have hands instead of hooves. No wonder Twilight has so much trouble coming up with a spell; she might be able to carry a tune when the singing mood strikes her, but that doesn't mean she understands musical theory.
In the first movie, Pinkie asks Twilight if she has a twin sister. Her innate sense telling her it's not "her" Twilight? Maybe... or maybe it's the fact that human Twilight wears her hair differently, wears glasses, dresses completely different, and likely has a much different demeanor. No wonder she didn't think they were the same person.
It make sense that Trixie would be one of the best performers (her band is semifinalist and should have been a finalist), since she is, after all, a performer even in her pony self. It is not only the catchy song, but also the showmanship what give her and edge, and since she does not have her unicorn magic in this world her showmanship must be better to compensate the lack of true magic in her shows. That could mean that ponies specialized in magic like her developed more their secondary skill in the mirror universe since they don't have true magic at their disposal, that could explain why Human Twilight seems to be going full scientist.
Also regarding Trixie, her band seems to advance in the competition playing only one song ("Tricks Up My Sleeve"), even though everyone else plays something different each round. This makes Trixie a One-Trick Pony.
Alternately since the Battle of the Bands was originally just a concert with no winner, it would have presumably just been one performance. So Trixie's band would only have one song prepared. It was only changed to a contest last minute. The Rainbooms just have more songs because Rainbow Dash loves to write them.
The Dazzlings being seahorse-like Sirens evokes images of Generation One Sea Ponies (their true forms being legless hippocampi, their tendency to sing a lot). Now there's a way to bring back a legacy character a significant portion of the older fandom has been looking for!
This one takes a bit of explanation. In the original "Music to My Ears" short, near the end, we see Vinyl Scratch/DJ-Pon-3 going into Mr. and Mrs. Cake's cafe. During the slow-mo sequence, we see her pass by the Humane Six, minus Sunset Shimmer, Twilight, and Spike. In the movie proper, when the full Humane Eight are present and catching up, if you look closely, you can see Vinyl Scratch walking up to the counter. You can also see her in the cafeteria just before the Battle of the Bands song. In both cases, she's wearing her headphones. This may not seem like much until the end, where she reveals that she wasn't affected by The Dazzlings Music because she was listening to her own music and never took off her headphones. A very subtle hint during the film is that at least one scene which catches Vinyl in the background shows her bobbing her head in rhythm that is completely out of sync with the Dazzlings' song, showing that she's going by the beat of her own drummer, to speak.
After the events of the first film, the entire school sans the Humane Five was at best nervous, at worst downright hateful, towards Sunset Shimmer. After the events of the second, things have improved. Granted, she did help to save the school (and probably the entire world) from the Dazzlings' plot, but consider this as well; under the Dazzlings' spell, the entire school was at one another's throats and acting like jerks. Exactly the way Sunset Shimmer had acted before the end of the first film. It's a little easier to forgive someone else's mistakes if you've made the same yourself.
The end of the film basically created a Plot Parallel between Celestia having Twilight learn about friendship while living in Ponyville, and Twilight helping Sunset do the same while living in the human world. Like Celestia, Twilight won't always be there to help Sunset but she's able to help out in a pinch, and they have a means to communicate despite the distance between them. The only main difference is that here, Twilight is doing this less as a Princess, but more as a friend to Sunset, but there's still a lot she can teach her.
Celestia and Twilight had a very similar relationship in season 1, as shown by the other ponies' shock at Twilight not bowing like the rest of them. Twilight is building a very similar relationship with Sunset Shimmer as that of Celestia with her.
Presuming that the portal back to Equestria did not stay open for the day or so that Twilight stayed there (as who knows what havoc that would have caused), how did Twilight get back to the pony-verse? Considering that once the companion book to Sunset's was put on the magic mirror device, it activated without further unicorn magic, all Twilight would have to do is have Sunset write in her book and have one of her pony friends see the message and put the book back on the stand.
Friendship games disproves this, the portal is permanently active now.
During the final battle, DJ Pon-3 keeps her earphones on all the while. But she didn't need to isolate herself anymore, wouldn't she want to hear the music of the Rainbooms since she's helping them? Oh, wait, she's right in the middle of four big loudspeakers, strong enough to blast away the Sirens! She can hear the music quite well, and in fact would need the protection for her ears.
It's a blink and you'll miss it moment but Spike is only big enough to hug one leg (as opposed to glomping everyone else). So which leg does he hug? Rarity's.
Might crossover with Fridge Horror and Fridge Sadness. Sunset tried to confront the Dazzlings herself, but ends up being put upon by the Dazzlings' seeds of doubt. What's interesting is that this is happening in a dark hallway. In the previous film, it was Sunset (back when she was still cruel and dishonest) who caused Twilight to lose confidence after confronting her in a dark hallway as well. Just imagine what was going through Sunset's head after the Dazzlings left her broken and alone. Probably something like, "Was I really this awful to Twilight the last time she was here? Oh, Twilight, I'm so sorry."
The end of Equestria Girls has Twilight reaching out to help the defeated Sunset back to her feet — Sunset is a bit hesitant to take it, but does so in time. In their first encounter in Rainbow Rocks, after Twilight falls out from the portal, Sunset's first act is to offer a similar hand to help Twilight up, and here, Twilight is hesitant to take it but eventually does. Forward to the end, where Sunset has started singing after the Rainbooms have been knocked to her feet — she reaches out her hand to help Twilight up, who takes it without any hesitancy.
The kitchen scene is stated in the DVD commentary to be a last minute addition, and while it takes advantage to add in the humorous appearance of Maud Pie, it brilliantly solidifies the friendship between Twilight and Sunset by having them compare and contrast their lives and finding despite their separate worlds they are a lot closer than they think. The end with Sunset writing off to Twilight is made much more heartfelt as a result.
The Dazzling's "Let's Have a Battle (of the Bands)" song is diametrically opposite of "The Cafeteria Song"/"Helping Twilight Win the Crown" song from the first film, foisting discord and dislike among the students in the cafeteria that the Manes had repaired from the first song, in the cafeteria.
Of course the Humane Five and Twilight wouldn't have access to the Elements of Harmony the way they did in the first film — the Elements, including the one in Twilight's crown, had been returned to the Tree of Harmony.
It seems convenient that Princess Celestia just so happened to send Sunset's journal to Twilight the exact moment the Humane Six needed her. However, when you consider that that book is, other than the closed mirror, the ONLY connection to the Human world in Equestria, it makes sense why Celestia would send it to Twilight; so she can keep in contact with her new friends.
It was stated the Humane Six were unaffected by the Dazzlings' spell due to having the magic of the Elements of Harmony within them, but why wasn't Sunset Shimmer affected when it was clear that their music can affect ponies too? She has a Seventh Element!
Or more simply, if ponies are affected by the Sirens at full power, in the Dazzlings' weakened forms anybody with a bit of magic inside them can resist, and Sunset Shimmer being a former unicorn is enough. Plus let's not forget she was changed by the crown too; even if this change was powered by ambition rather than friendship, she still can have residual magic in her, as seen with the climax.
Why didn't Twilight immediately receive Sunset's hand after going through the portal? As the movie takes place after "Twilight's Kingdom", in which Twilight is betrayed by a "reformed villain" (Discord), she was worried it might happen again.
Several people have commented on the fact that the Dazzlings' songs are better sounding than the Rainbooms' singing. And that makes perfect sense! The Dazzlings are sirens who have magical powers which fuel their singing. The Rainbooms are an all-girl garage band. The Dazzlings are meant to be alluring. The Rainbooms sing for the love of it and aren't professionals. It can also imply that the audience isn't safe from the Dazzlings' enchantment...
Why is the real human Twilight Sparkle not at Canterlot High School? Because (a) she's so intelligent that she graduated early for her age, perhaps even already has a PhD; and (b) she is as socially reclusive as pony Twilight was at the beginning of MLP: FIM and therefore has no friends there to stay in contact with.
Photo Finish's bandmates, Pixel Pizzaz and Violet Blurr, have noticeably more elaborate looks than you would expect from such minor characters (leaning into Elegant Gothic Lolita). But then, Photo Finish is part of the Fashionista clique, and so are her friends, so it makes sense. Where Trixie's strong point is spectacle, the Snapshots' strong point is fashion.
At the end of the movie, Sunset Shimmer has started sending Twilight friendship reports, effectively making Twilight a mentor to Sunset the way Celestia mentored the two of them. Because Twilight learned everything about friendship that she knows from Celestia, this means that Sunset is still receiving lessons from Celestia, albeit indirectly.
Why are the Sirens Hollywood Tone-Deaf after their powers are gone? Because they've relied on magic to do the singing for them their whole lives. They've never had to learn how to carry a tune or properly hold a key the way normal singers do. With no professional training at all, their performance makes a lot more sense.
Combining Rainbow Rocks with the series episode Slice of Life, we actually get the implication that Vinyl is hard of hearing. (She lip reads Dr. Hooves; and she has trouble syncing with Octavia's music across the room, unaware that it isn't meshing until Octavia indicates as much, and is only able to do it after a much greater effort.) Which explains why she can do things like, say, sit in the middle of those huge speakers, or cross the street or drive with her headphones on: she doesn't rely on her hearing when it comes to being aware of her surroundings, and she's used to turning the music up loud to feel the bass as much as actually hear it.
Bit of an addition to this. You listen to loud music a lot on headphones, and you WILL find that you're turning the volume up just slightly to hear the TV or similar, and the headphones seem to need to be turned up a bit more to be heard. Vinyl has been doing so probably for a long time, so while she's not quite reached levels of being deaf, she does have problems hearing things properly.
The Dazzlings have been reduced to normal human girls. What are they going to do now? They didn't get any offers of friendship like Sunset did, and if they keep going to school they'll probably be rejected like she was except they'll have no one to turn to. (This will be especially bad if we don't see them in the next movie).
Something else to think about; they were banished to the human world by Star Swirl the Bearded, who was last known to be active in Equestria right around the time of Nightmare Moon. It's possible that what little magic they had, they were using to extend their lifespans. Without their gemstones, they have no magic. What if the thousand years or so catch up with them?
Which brings up a few more questions: were the Dazzlings really banished to the human world for 1,000 years or so? Does that mean they were around during (what would be) the Imperial eras of the real world? Or, because of the difference in time/life-span between the two worlds, did they stay for a much shorter time?
According to My Little Pony: FIENDship Is Magic, when the Dazzlings were sent through the portal, they arrived in the human world a few months or years before the events of Rainbow Rocks.
At the beginning of the film, the Dazzlings used terms like "fast food" and "meal" to describe absorbing negative emotions, making it sound like they need to do so for nourishment. Without their necklaces, it's possible that they could starve to death.
Sonata Dusk did get excited about it being "Taco Tuesday" and seemed eager to have regular food, so perhaps they don't entirely rely upon their magic-absorbing for nourishment.
But that's a similar argument to the Cullens being able to eat regular human food. They can, but it doesn't necessarily mean they are able to survive on it. The same could be said for the Sirens.
Also, how will the sirens get food? Most people wouldn't give them food, they will likely be afraid of the main 5, they can't be arrested as canterlot high has no proof they did anything wrong, and they are never shown to have homes.
This is the most likely explanation, which itself opens up some more Fridge Horror. Sure, it's their magic that made them the massive threat they were, but it should be noted that Adagio is a Manipulative, borderline Magnificent Bitch who does not always need magic to get people to do what she wants. Remember how Sunset Shimmer practically ruled the school with an iron fist despite not having any powers (at first)? Assuming they really got away with just a depowering, this may not be the last time we hear from the Dazzlings.
Another piece of Fridge Horror that ties to the main pony continuity: When exactly in Equestria's past did the Dazzlings wreak havoc?
If they had been at large pre-Unification, it would surely have been their influence that drove the Three Tribes apart and made it possible for the Windigoes to begin preying on them.
If it was post-Unification, they might have nearly ruined the early Equestrian unity before Star Swirl intervened and banished them.
Considering the comics, they may have been at work around the time that Princess Luna became Nightmare Moon, or immediately thereafter. It would certainly explain why Star Swirl the Bearded was the one to deal with them rather than Princess Celestia, but suggests some further Fridge Horror — they might have been a factor in Luna's fall from grace.
Simple thought exercise: What atrocities did the dazzlings do during the thousand years they were banished? Remember, EQG-Earth didn't have magic that could be used to stop them until Sunset Shimmer brought the Element of Magic.
Methinks they were just feeding off the negative energy of others, like they were doing in the intro of the movie... though what's weird is that they discuss the concept as if it was new to them.
After what she did in the first film, Sunset Shimmer has become a social pariah who can barely go about her day without people glaring at her and talking behind her back, and she knows pretty much exactly what they're saying about her. In real life, a lot high school students subject to this treatment tend to want an escape from the pain... let's be grateful the Humane Five were there to help her pick up the pieces and stick by her, or else Sunset's story could have gone a lot worse than it did.
This isn't the first time a character has received this kind of treatment in the show. After Discord's reformation, everyone except Fluttershy remained quite nasty to him, which was probably what prompted him to join Tirek in the first place. Who's to say that Sunset wouldn't have sided with the Dazzlings if the Humane Five refused to accept her as well?
Some Horror mixed with Brilliance; Sunset Shimmer wasn't a part of the Rainbooms. While no reason is stated in the film for her not being included in the band from the start, part of it might have been reluctance on Sunset's part. She's smart enough to theorize that the transformations they undergo could be the result of what happened with Twilight's crown in the first film, and she fears turning into a "raging she-demon" again. Didn't turn out to be the case in the end, but it's a valid fear on her part.
The Dazzlings do formulate a reason when they're talking to Sunset to make her doubt: that the Rainbooms didn't include her because her low popularity would have cost them the contest. We don't know if it's true, though.
It's entirely possible it was all of the above; Rainbow didn't include her because she thought Sunset would ruin their chances, but it was probably Applejack who suggested they not ask her lest she go Drunk with Power again from all the attention (with Pinkie Pie enthusiastically pointing out how this would happen). As for Rarity and Fluttershy, Rarity may have suggested a third reason to not ask her ("Sunset Shimmer might not want the extra attention; just look at how she gets treated now!") and Fluttershy would either have sided with Rarity or meekly suggested they ask her anyway because it's not fair to leave her out but as she's Fluttershy, was promptly ignored.
Note that technically, Sunset was part of the band, as we see her handling the sound equipment a few times. She wasn't doing a terribly good job at it, though (as shown with the Is This Thing On? moment), so it's probably better for the Rainbooms to let Vinyl Scratch handle this afterward and have Sunset plays with the band.
The Dazzlings' songs cause those listening to be ultra-competitive and give into hate. We watched, we saw it happen on screen, and and we're still loving it! Just imagine what they could do if they were real!
Despite being centuries old in the human world, The Dazzlings are still biologically teenagers, presumably because feeding on hate keeps them young. However, their amulets were broken at the end of the movie, turning them into regular girls. This implies that their natural lifetimes were significantly cut short.
Jossed by Fiendship is Magic. They've only been in the human world for a short time.
Fiendship has been contradicted by the show and is therefore no longer considered canon.
Just the idea of what the sirens could've done if the girls didn't stop them. What if they had gotten enough power to manipulate a world leader? What is a better source of hatred and rage... than a war.
Wouldn't having people kill each other reduce their supply of hatred and power?
Billions more where those ones came from. And as we saw during their brief cameos in Shadow Play the Sirens weren't concerned about the wellbeing of those they affected seeing as they drove them to physically attack each other.
Ignoring the global application of the Dazzlings's hate plague, suppose it had caused something more disruptive to occur in the school itself, like a Useful Notes/Columbine sytle school shooting?
Wouldn't having people kill each other reduce their supply of hatred and power?
There's always more people to replace the ones lost, and the increased amount of negative energy they'd receive from such an action may make it worth the loss.
The spell didnt turn everyone "Evil", it just turned them overall angry and competitive with no inhibitions. Do you honestly think high school kids filled with irritability and no inhibitions doing sabotaging pranks takes a special kind of evil? Hell, even Adagio established that all they were doing to school kids was giving them an instant "worst day, lash out at friends" attitude, otherwise they wouldn't be able to absorb the Mane 6's energy by manipulating them into that state without directly using their magic. So what happens if someone thinks the best way to eliminate the competition is by killing them off?
Star Swirl the Bearded sending such creatures to the human world believing they can't cause trouble there because there is no Equestrian magic presents three rather troubling thoughts:
Starswirl banished the Sirens to EQG-Earth, and, as far we know, didn't check up on them. You know another movie where checking up on the enemy could have prevented the plot? Star Trek II: The Wrath of Khan.
For that matter, has anyone checked up on them since the Battle of the Bands?
What other creatures could he have inflicted on the completely unknowing populace of the human world that can now wreak havoc thanks to the newly introduced Equestrian magic? Changelings? Windigos? Something we've yet to see that is much much worse?
What could the humans there do with this very powerful otherworldly magic? What if there happened to be an ambitious, intelligent, and morally bankrupt youngster at that very school who decided to see what he or she could do with it now that he's seen it in action?
Finally, what if humans as a whole figure out that some creature from a parallel universe was basically using their world as a convenient can in which to seal evil, don't like that one bit, and decide Equestria is a threat? They might just try to seal his portal, or they might decide to warm up the nukes and fight back.
DJ Pon-3 never takes off her headphones, not even when driving. There's a reason wearing headphones when driving is illegal in many areas.
As far as I know, the only time we see her driving with headphones is when she's driving up the hill to help the Rainbooms in the final battle. She probably kept them on because she didn't want to risk falling under the Dazzling's spell at the last moment.
Well, the Music to My Ears short did show that she is the kind of person who would cross the road while listening and dancing to music.
This movies establishes a few more rules for the portal and magic into the human world. Sunset's book retain its enchantment, as do the Dazzlings necklaces and the Element of Magic from the previous movie. That's because unlike living beings, they aren't transformed, as the first movie establishes that Twilight can't use magic because her horn is gone.
This movie marks the point in the series where the villains start becoming genuinely threatening, and The Stinger establishes that there is indeed a human Twilight. Combined with the fact that human characters tend to have roughly the same personality their pony counterpart had before character development. Human Twilight's appearance makes it even easier to assume there's a human Sunset out there too, but the other two points suggest that if the Rainbooms ever bump into her, she might prove a far more dangerous foe than "our" Sunset did.
The Dazzlings spent most of the movie at Canterlot High. The portal back to Equestria is in the Wondercolt statue out front, and Twilight seems to have left it open when she came through. One of them could have very easily found the portal by accident.
After seeing the Sirens in action in the Friendship Is Magic episode "Shadow Play", we can conclude that the Rainbooms were lucky that even the Dazzlings' projections of their true forms were still far from their full power. Sure, their sonic attacks could dispel Twilight's sparks, push away the girls and apparently hit hard enough to temporarily put them in some sort of stupor, but that was still a lot less dangerous than the Breath Weapon demonstrated in "Shadow Play", which can vaporize rocks. Had the Sirens regained powers of this caliber, the Equestria Girls would have been in real trouble.
Even worse, at their full power they drove their victims to actually attack each other instead of just arguing and were so strong even Starswhirl and the Pillars couldn't defeat them and had to resort to trapping them in anouther world. The Humane 7 working on just their leftover magic from Twilight's crown wouldn't have been able to match that.
When the dazzling's shed their human bodies, you can see that their amulets are a part of their siren forms. Later, the amulets are broken into several pieces and fall on the floor. What's worse, without the amulets, they can't sing. Does that mean that the amulets are like throats, And losing the amulets was like getting their throats ripped out? Adding to that is the fact that they probably aren't actual rock, the dazzlings survived an attack that destroyed their gemstones.
The dazzlings sing an amazing song about how you are being hypnotized by their music. Repeated listening will make it feel like they really are.